Twenty people were killed and around 100 more injured when a passenger train plunged off a bridge in western India after hitting a boulder, railways minister Lalu Prasad Yadav said.

The accident occurred early morning on a bridge between Veer and Karanjadi stations some 200 kilometres (124 miles) from Bombay in western Maharashtra state, Yadav said.

Television footage showed mangled coaches of the Matsyagandha Express lying on their sides while two carriages hung precariously from the 90-foot (27-metre) high bridge.

Yadav rushed to the site and promised to punish rail officials if negligence was established as the cause of the crash.

Officials at the site said the engine of the crowded train, which was travelling at about 90 to 95 kilometres (55 to 58 miles) per hour, slammed into a boulder that was on the tracks.

B. Rajaram, managing director of Konkan Railways which operates trains in the region, said the crash occurred despite the precaution of installing steel nets across loose rocks.

A doctor from a nearby hospital said 60 of the injured were being treated in his facility. Fifteen of them were in a critical condition, he said.

The train had been travelling between the southern port city of Kochin in Kerala state and Bombay.

Prime Minister Manmohan Singh, meanwhile, said he was "deeply shocked" by the crash and added that he had ordered Yadav to provide all possible help to the survivors.

President A. P. J. Abdul Kalam too expressed his condolences to relatives of those killed and in a message said he hoped "all possible efforts and rescue measures will be made to provide relief and special care for the injured."

Rajaram's Konkan rail route, which traverses some of the most scenic parts of western India, links Maharashtra with the tourist resort state of Goa and southern India.

The 760-kilometre (470-mile) route is connected by more than 100 major bridges, about 1,800 minor bridges and 92 tunnels.